Mascot search result scores of digested proteome extracts from three different ostrich bone specimens analysed months apart and the similarity to the ostrich (Struthio) sequence as a percentage. Note that the first tryptic peptide of the emboldened sequence was also matched in every sample without the missed cleavage at the K residue. Underlined residues indicate post-translational modification (oxidation of P/K; deamidation of N); scores in parentheses represent higher scores with deamidated peptides or with one additional oxidation. m/z, mass-to-charge ratio.

peptide sequence

m/z

CC1254

CC507

UM902

similarity (%)

BrachyA1/TrexA1

GVQGPPGPQGPR

1161.6

57

53 (60)

59 (65)

100

BrachyA1

GPSGPQGPSGAPGPK

1305.6

71

74

53 (80)

100

BrachyA1/TrexA1

GSAGPPGATGFPGAAGR

1458.7

94

120

123

100

BrachyA1

GETGPAGPAGPPGPAGAR

1531.7

84

85

66

100

BrachyA1

GLTGPIGPPGPAGAPGDK

1589.8

58

75

45

100

BrachyA1

GLTGPIGPPGPAGAPGDKGEAGPSGPPGPTGAR

2878.4

45

45

36 (44a)

100

BrachyA2/TrexA2

GLPGESGAVGPAGPPGSRb

1577.8

70

76

78

89

BrachyA2

GSNGEPGSAGPPGPAGLR

1608.7

80 (93)

58 (79)

71

100

BrachyA1/TrexA1

GATGAPGIAGAPGFPGAR

1571.8

74

73

58

100

TrexA1

GAPGPQGPSGAPGPK

1305.6

69

62

46 (71)

100

TrexA1

GVVGLPGQR

897.5

50

46

50

100

aScore with one additional oxidation.

bPeptide was considered unique to T. rex but see electronic supplementary material, S1–S6.